Bio-110 Chapter 13A & 13B
Imagine that four people are infected with HIV from a common source (an infected blood sample). Initially, the patients' HIV populations are genetically identical. By the time they develop full-blown AIDS, how would the viral populations of the fourpatients compare?
Each patient's viral population would be unique, specifically adapted to deal with—and overcome—his or her unique immune system responses.
How did Dr. Allison test his hypothesis that sickle cell disease was connected to malaria?
He expanded his study area beyond Kenya to the rest of East Africa to see if malaria and sickle disease were connected. He evaluated blood samples for malaria parasites and the presence of sickle cells. Dr. Allison gathered blood samples from more than 5,000 children in East Africa. He analyzed the samples to identify malaria parasites and sickle cells. He found that children carrying the sickle cell character (or trait) had a lower parasite count, as if they were partially protected against malaria.
In sexual selection, individuals with certain inherited characteristics are more likely to obtain mates than other individuals. This often results in ____________, differences between the sexes in size, appearance, and behavior
Sexual dimorphism
Which of the following does current research most support?
The common bedbug lived with bats first, then humans.
Sickle-cell disease is caused by __________.
a recessive allele Only homozygous recessive individuals will have the disorder.
In a type of sexual selection often called _________________, individuals of one sex (usually females) are choosy in selecting their mates. This choice is often based on the showy appearance or behavior of the male.
Mate Choice
The phrase Darwin used to describe his broad theory of evolution is ''descent with __________________."
Modification
A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than individuals with other characteristics is called __________.
Natural Selection
Darwin proposed a mechanism for how evolution occurs, which he called "________"
Natural Selection
The data suggest that, over time, _______________resulted in the evolution of shorter wings in the cliff swallow population.
Natural Selection
A process in which organisms with certain inherited characteristics are more likely to survive and reproduce than individuals with other characteristics is called __________.
natural selection
Natural selection __________.
relies on variation among individuals in a population
Color is an inherited trait in beetles. If brown beetles move into a population from a nearby island, which of the following statements is correct?
Gene flow causes the frequency of the brown allele to increase. Gene flow occurs when individuals move into or out of a population, changing the allele frequencies in the population. In this case, new brown beetles in the population cause the frequency of the brown allele to increase.
Remember that color is an inherited trait in beetles. Which of the following is an example of natural selection?
Green beetles leave more offspring than brown beetles because they are better at finding food. Natural selection occurs when organisms with one inherited trait survive and reproduce more than organisms with other traits
In 1949, Dr. Tony Allison observed a high frequency of Kenyans carrying the sickle cell allele in coastal areas and near Lake Victoria, but a lower frequency in the highlands. What did he hypothesize?
He hypothesized that there was a connection between malaria and sickle cell disease.
As proposed by Darwin, what sorts of traits are favored by natural selection?
Heritable traits that help individuals survive and reproduce more successfully than others in the same population.
The human immune system cannot effectively suppress the HIV virus on its own. What key feature of HIV makes it so hard to beat?
The HIV virus has an extremely high rate of mutation.
How does Dr. Allison's work provide an example of natural selection in humans?
In areas without malaria, individuals with two sickle cell alleles reproduced at lower rates than those without sickle cell disease. In areas with malaria, individuals with one sickle cell allele reproduced at higher rates than those with no sickle cell alleles.
In some populations, 1 in 500 people have sickle cell disease. What reason does the film give for why a potentially deadly, inherited disease is found at such high frequencies?
Individuals with one sickle cell allele are protected from malaria and do not have sickle cell disease, thus keeping the allele in the population. People with one sickle cell allele are protected from malaria, but do not have sickle cell disease. Protection from malaria comes at the cost of more sickle cell disease in the population.
Two key observations underlying natural selection are that members of a population vary in their "__________"
Inherited Traits
The population of American bison used to number in the millions of animals. Hunting and other problems greatly decreased the number of bison to about 1,000 animals. But today, the numbers are recovering to estimates of more than 200,000 animals. This crash in the population of bison and recent recovery is a good example of _____.
the bottleneck effect The dramatic decrease in the total numbers of bison to a low level followed by a recent dramatic increase reflects the bottleneck effect.
Which of the following is an example of natural selection that has been seen in our lifetime?
the evolution of antibiotic-resistant bacteria
Which of the following is true?
The bedbug that feeds on humans can interbreed with the bedbug that feeds on bats, though they do not typically do so.
If a person has two normal copies of the hemoglobin allele, which statements are true?
The person is homozygous at the hemoglobin locus. The person is susceptible to malaria. A person with two copies of any allele is homozygous. A person with two normal copies of the hemoglobin allele is more susceptible to malaria than someone with a sickle cell hemoglobin allele.
Predict what will happen to the frequency of the sickle cell allele in areas where malaria has been eradicated.
The sickle cell allele will decrease in frequency.
Shorter wings are a(n) ______________ in this population. Alleles for shorter wings were ____________ in the general population.
adaptation already present
This unequal reproduction in a population leads to the gradual accumulation of "______" to the environment
adaptations
From 1984 to 2012, the wing length of cliff swallows in the general population generally
decreased
Blue poppies native to China are grown at a plant-breeding center in California. Those with the thickest leaves survive and reproduce best in California's drier climate. This evolutionary adaptation of the poppies to their new environment is due to __________.
directional selection
The relationship of the genome to an organism is similar to that of the __________ to a population.
gene pool The gene pool represents all of the genetic information in the population, and the genome represents all of the genetic information of the organism.
The evolution of populations due to chance is
genetic drift Genetic drift describes the evolution of a population due to chance.
In a population with brown and green alleles for color, genetic drift
has more effect on the evolution of a small population. Genetic drift affects the evolution of small populations more than it affects the evolution of large populations.
During the same time period, the wing length of cliff swallows killed on the roads generally
increased
In most years where data was collected, the wings of cliff swallows killed on the roads were ____________ than the wings of swallows found in the population at large.
longer
When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Today, some 30 years later, a much smaller proportion of these insects die when sprayed. The reason fewer insects are being killed is that __________.
many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics
"Differential success in reproduction" is just another way of saying _____.
natural selection
The smallest unit that can evolve is a _____.
population
Scientists have warned doctors of the danger of their increasing use of antibiotics (for instance, penicillin) for treating minor illnesses. They are concerned because _____.
strains of microorganisms that are resistant to these drugs will increase
In a population of bears, which is most likely to be considered to have the greatest Darwinian fitness?
the bear that leaves the most descendants
The "_____" of life arises from the adaptation of species to different habitats over long spans of time.
Diversity
Compare sickle cell disease and malaria.
Sickle cell disease and malaria are both potentially lethal diseases. Though malaria is an infectious disease and sickle cell disease is inherited, both can cause life-threatening conditions.
A population is __________.
a group of individuals of the same species occupying a given area
Anatomical and molecular homologies:
Similar forelimb anatomy in different species of mammals Same genetic language of DNA and similar genes in yeasts, fruit flies, and humans.
_______________ favors intermediate phenotypes, selecting against phenotypes at both ends of a range and reducing variation.
Stabilizing Selection
What observation concerning the geographic distribution of species on the Galápagos Islands helped Darwin formulate his ideas about the mechanisms of evolution?
Darwin observed that most of the animals that inhabit these remote islands are not found anywhere else in the world, but they resemble South American species. Furthermore, each island has its own unique species.
Observation of natural selection in action:
Development of Pesticide resistance in insects Changes in average beak size in finches following dry or wet years
__________________ favors phenotypes at one end of a range and is common in periods of environmental change.
Directional Change
_______________ favors phenotypes at both ends of a range over intermediate phenotypes. This type of selection may occur when the habitat is varied.
Disruptive Selection
Darwin inferred that those organisms with traits best suited to the environment ten to leave more "_____" than other members of a population
Offspring
Which one of the following statements most closely agrees with the theory of evolution by means of natural selection, as put forth by Darwin?
Organisms better adapted to their immediate environment are most likely to survive and reproduce. Success in the struggle for survival is not random but depends in part on the hereditary constitution of the surviving individuals. Those individuals whose inherited characteristics fit them best to their environment are likely to leave more offspring than are less fit individuals.
Which of the following is true?
Over time, the bedbug that feeds on bats will likely become less similar to the bedbug that feeds on humans.
Which of the following is true?
Populations of bedbugs that feed on humans are more likely to be resistant to pesticides than populations of bedbugs that feed on bats.
Which one of the following was an assumption of Charles Darwin's theory of natural selection?
Populations produce more offspring than their environment can support.
Shorter wings allow cliff swallows to take off from the ground more vertically, enabling them to better avoid oncoming cars. As a result, cliff swallows in populations near highways with ____________wings have a survival advantage.
Shorter
Which of the following led to the greatest decline of bedbug populations in the mid twentieth century?
The use of pesticides, namely DDT.
The fossil record is incomplete because
Transitional forms that link whales with land -dwelling ancestors that are now extinct Discovery of bones from many different dinosaur species
Biogeography:
Unique collection of marsupial mammals in Australia Resemblance of island species to nearby mainland species
All of life is related through common ancestry, accounting for the "______" of life.
Unity
Natural selection is best described as _____.
a filtering process that fine-tunes the traits of populations by sorting among existing, randomly produced variations
HIV has become an important source of mortality for humans. If AIDS persists as a major factor for humans for many generations in the future, natural selection theory predicts that _____.
any heritable traits that help humans survive and reproduce in the presence of AIDS should become more frequent over time
Which of the following is the study of the geographic distribution of species on Earth?
biogeography
Evidence from molecular biology supports the theory of evolution by showing that __________.
closely related organisms have more similar DNA and proteins Evolutionary relationships among species are reflected in their DNA and proteins. If two species have similar libraries of genes and proteins, with sequences of monomers that match closely, the sequences must have descended from a common ancestor.
In evolutionary terms, an organism's fitness is measured by its __________.
contribution to the gene pool of the next generation
Imagine that a new population of humans is established on a new planet from ten randomly selected people in your biology class. Over thousands of years, the descendants of those ten people reproduce and prosper, but do not reflect well the diversity of humans on Earth. This change in the diversity of people on the new planet is an example of _____.
the founder effect The founder effect involves the colonization of a new habitat by a few individuals who do not represent all of the diversity of the parent population. The result is a new population with a different frequency of traits.
If color is an inherited trait in beetles, and birds are more likely to eat brown beetles than green beetles,
the frequency of the green allele will increase. If birds are more likely to eat brown beetles than green beetles, then green beetles will survive and reproduce more than brown beetles. This causes the frequency of the green allele to increase.
Which of the following is a requirement for natural selection?
variation in individuals